In surgical operations, it is often necessary for the surgeon to be able to grasp and/or manipulate bits of tissue precisely, particularly when the surgeon is relatively remote from the surgical site, as in performing endoscopic procedures. There are many different instruments known to persons skilled in the art for this purpose, e.g., graspers, forceps, disectors, etc. Often the grasping or manipulating is achieved by means of an instrument having a 2-part handle mechanism, a jaw mechanism comprising a pair of opposed mutually confronting jaws, and jaw supporting and operating means coupling the handle mechanism and the two jaws for causing the jaws to be moved into and out of a closed relation with one another by the surgeon's manipulation of the handle mechanism. In a typical prior art instrument, the jaw supporting and operating means comprises a relatively long hollow shaft fixed to one part of the handle mechanism, an elongated operating shaft or rod disposed for telescopic movement within and relative to the hollow shaft and adapted to cause opening and closing of the jaws according to the direction of said telescoping movement, and means connecting the rod to the other part of the handle mechanism so that telescoping movement of the rod and shaft is produced when the two parts of the handle mechanism are moved toward and away from one another. In some instrument constructions, two jaws are pivotably attached to one end of the outer shaft, and a linkage operated by the inner rod causes the jaws to be opened or closed in response to telescoping movement of the shaft and rod. In other cases the jaw mechanism comprises a pair of spring-like jaws carried entirely by the rod, with the shaft acting as a collet to force the jaws together when the telescoping movement is in one direction and release the jaws so as to allow them to open when the telescoping movement is in the reverse direction.
These and other known forms of surgical instruments designed to grasp or manipulate tissues, vessels or organs are commonly provided with some form of locking means for locking the jaws in a tissue-gripping position so that during a surgical procedure, a surgeon may let go of the instrument to attend to some other task of that same surgical procedure without fear of the instrument failing to retain its grip. Such locking means take various forms, e.g., interlocking ratchet teeth on confronting portions of a two part handle mechanism of the type where each of the two parts has a hole for accommodating a finger or thumb of the surgeon. Other types of known locking mechanisms may use a lever or a button member for engaging or disengaging the locking means.
Prior grasper-type surgical instruments are characterized by one or more limitations and disadvantages. For one thing, they are usually designed so that the force with which the surgeon can cause the instrument to grasp tissue is a function of his manual strength and the strength of the components of the instrument. Consequently the grasped tissue may be traumatized as a result of being grasped too tightly. Moreover, in the case where the jaws have teeth or serrations and/or angular rather than rounded edges, the jaws may actually sever or puncture the grasped tissue. Locking mechanisms also present disadvantages. In the case of a ratchet-type locking means, it may be necessary to deliberately warp a portion of the instrument in order to disengage the interlocking ratchet teeth. This is disadvantageous in that the force required to be applied by the surgeon to cause the required warping action may result in a reactive displacement of the instrument relative to the patient being operated, and also may require an awkward movement of the surgeon's fingers. The other types of locking mechanisms described above almost invariably require the surgeon to operate a separate control, such as a lever or button, to disengage or engage the locking mechanism. Such action by the surgeon may be inconvenient and in addition the presence of the separate control may render the instrument less comfortable to hold and maneuver.
Another disadvantage of some prior grasping instruments is that they are highly asymmetric about the longitudinal axis of the operating rod, so that it is difficult to reorient the jaws by rotating the instrument without causing an unwanted lateral excursion of the jaws. It is for this reason that many grasping-type instruments are provided with rotatable shafts and/or operating rods, plus operating means for causing such rotation. Usually this means that the surgeon must operate a wheel, knob, or other movable control member to effect the desired rotation. Depending on the nature and location of such control member, the act of reorienting the jaws can be overly distracting to the surgeon and may require the surgeon to hold the instrument in an uncomfortable or awkward manner or even require him to use a second hand to effect the rotation.
This invention results from recognition of the fact that the utility and safety of a surgical instrument intended for grasping or otherwise manipulating living tissue or a blood vessel or a human organ is diminished if the instrument lacks suitable means for limiting the clamping force exerted by the jaw and has separate controls for locking the jaws or effecting relative rotation between the jaws and the handle mechanism.